Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
ivy.chris
 
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Exponent Crazy

by ivy.chris Sat Aug 29, 2009 4:55 pm

(6.804)^6(1.701)^-13
__________________
(2)^19(3.402)^-7


The expression

(6.804)^6(1.701)^-13
_____________________
(2)^19(3.402)^-7

can be simplified as follows:

(6.804)^6(3.402)^7
_________________
(2)^19(1.701)^13

Can someone please explain which exponent property is applied to "flip" the 1.701 and 3.402 from the numerator to the denominator (and vice versa)

Thanks!
sunny.jain
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Re: Exponent Crazy

by sunny.jain Fri Sep 04, 2009 4:45 am

(6.804)^6(3.402)^7
_________________
(2)^19(1.701)^13

==> (6.804)^6 * (2*3.402)^7
_______________________
2^19 * ( 4* 1.701) ^13

==> (6.804)^13 * 2^7
________________
2^19 * (6.804)^13 * 2^26

I hope its done now. Please check whether you have correctly given the first expression i used in my explanation. I copied it from you solution.
Kweku.Amoako
 
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Re: Exponent Crazy

by Kweku.Amoako Fri Sep 04, 2009 8:01 am

I think if you recognize that

6.804 = 2 * (3.402) = 4 * (1.701)...then the rest is easy to understand
bluescale
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Re: Exponent Crazy

by bluescale Tue Sep 08, 2009 6:11 pm

ivy.chris Wrote:(6.804)^6(1.701)^-13
__________________
(2)^19(3.402)^-7


The expression

(6.804)^6(1.701)^-13
_____________________
(2)^19(3.402)^-7

can be simplified as follows:

(6.804)^6(3.402)^7
_________________
(2)^19(1.701)^13

Can someone please explain which exponent property is applied to "flip" the 1.701 and 3.402 from the numerator to the denominator (and vice versa)

Thanks!


You can flip 3.402^-7 from the denominator to the numerator because it is raised to a negative exponent. The same is true (in reverse) for 1.701^-13.

Keep this rule in mind at all times: When you raise a number to a negative exponent, you flip it from the numerator to the denominator, or vice versa.

Some examples:

x^-2 = 1/(x^2)
1/(x^-2) = x^2
2^-2 = 1/(2^2) = 1/4
1/(2^-2) = 2^2 = 4

I hope that helps.
Ben Ku
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Re: Exponent Crazy

by Ben Ku Sun Oct 25, 2009 3:11 am

Can someone please explain which exponent property is applied to "flip" the 1.701 and 3.402 from the numerator to the denominator (and vice versa)


The relevant properties of exponents that allow you to "flip" terms are:
a^(-m) = 1 / (a^m)
1 / (a^-m) = a^m
a^m / a^n = a^m-n

Basically a negative exponent means to "flip" the term from top to bottom (or vice versa). bluescale gives some nice examples.
Ben Ku
Instructor
ManhattanGMAT
DRK53
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Re: Exponent Crazy

by DRK53 Wed Apr 11, 2012 7:53 pm

There is one step in this problem I am also perplexed about. How is it that 4^6 simplifies to 2^12? I know they are equal, but what rule allows for this?
tim
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Re: Exponent Crazy

by tim Wed Apr 25, 2012 5:38 pm

if you know they are equal, then you must be aware of the rule:

4^6 = (2^2)^6 = 2^(2*6) = 2^12

make sure you are very familiar with your exponents rules..
Tim Sanders
Manhattan GMAT Instructor

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arthi9487
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Re: Exponent Crazy

by arthi9487 Tue Dec 03, 2013 11:01 am

Kweku.Amoako Wrote:I think if you recognize that

6.804 = 2 * (3.402) = 4 * (1.701)...then the rest is easy to understand


How is someone supposed to recognize this? Is this a standard rule somewhere in the books?
RonPurewal
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Re: Exponent Crazy

by RonPurewal Thu Dec 05, 2013 10:46 pm

The thought process should be, essentially, "Those weird decimal values MUST be somehow related." (If they weren't, it would be impossible to simplify the expression.)

Once you have in mind the idea that there must be some sort of relationship, it's not too hard to notice that this number is twice as big as that one, and so forth.